Global positioning system (GPS) is currently the most widely used positioning system. Usually, the GPS satellites are located more than 20 kilometers above the surface of earth. GPS signal degrades significantly over such a long distance when it reaches the earth. Generally, a GPS receiver requires at least a sensibility of −130 dBm to acquire a GPS signal in a clear and open sky environment. In urban or indoor environment, the GPS receiver may require a sensitivity parameter ranging from −155 dBm to −160 dBm or more than −160 dBm to perform GPS positioning functions. Furthermore, the performance and accuracy of GPS positioning system will degrade dramatically due to any reflection, blockage and multi-path effect of GPS signals under urban or indoor environment.
With the digitalization of terrestrial analog audio broadcasting and analog video broadcasting technologies, which correspond to two mainstream standards, namely DAB (digital audio broadcasting) and DVB (digital video broadcasting)/ATSC (advanced television system committee) respectively, terrestrial digital broadcasting system (T-DBS), which includes DAB, DVB, and ATSC system, has an unparalleled edge over the global positioning system in terms of signal transmission power, signal transmission distance. Furthermore, the penetration ability of T-DBS signals is much stronger than that of GPS signal broadcasting at L1 carrier frequency level. Terrestrial digital broadcasting system can be used in environments such as basement, stair ways and underground parking lots where GPS positioning fails to perform. In addition, the use of the terrestrial digital broadcasting system can serve as a complement to the GPS in an urban environment where GPS positioning results become unreliable due to the densely built high-rises. Thus, it is to a hybrid positioning technology using T-DBS signal and GPS signal that the present invention is primarily directed.